FIG. 1 is a block diagram showing a conventional ultrasonic diagnostic system.
A conventional ultrasonic diagnostic system includes a probe 10, a main body 20, and a cable 30.
The probe 10 includes a plurality of transducers 11 and an analog beam former 13.
In FIG. 1, the probe 10 includes 64 transducers 11 and 8 analog beam formers 13.
The transducer 11 emits ultrasonic waves to a target point or a focal point F, according to a signal transmitted from the main body 20, receives reflected ultrasonic waves, and converts the reflected ultrasonic waves into analog electric signals.
In FIG. 1, 64 transducers 11 form sub-arrays in units of eight, but a number of transducers 11 included in a sub-array can be variously set to one or more.
The probe 10 may further include a plurality of analog signal regulators or analog front ends (AFEs) 12.
Maximum value of a signal output from each transducer 11 is different according to a channel. The analog signal regulator 12 controls a gain to amplify an output signal of a transducer 11 to a predetermined magnitude and output an amplified signal.
The eight analog beam formers (ABFs) 13 perform a beam forming operation on the analog electric signals output from the eight analog signal regulators 12 corresponding to the eight sub-arrays and outputs analog beam signals.
An analog beam signal can be represented by a sum of analog signals whose time or phase difference has been removed.
The look-up table (LUT) 24 of the main body 20 can store delay information of each channel according to the focal point F in advance. The LUT 24 may also store amplification ratio of each analog signal regulator 12 in advance.
The controller 23 of the main body 20 reads delay information and amplification ratio for a selected target point F from the LUT 24 and outputs the delay information and the amplification ratio to the analog signal regulators 12 and analog beam formers 12 of the probe 10.
The analog beam former 13 performs a beam forming operation on the signals received from analog signal regulators 12 using the delay information.
The analog beam signals output from analog beam formers 13 are transmitted to the main body 20 through a cable 30.
In FIG. 1, the main body 20 includes eight analog-to-digital converters (ADCs) 21 and a digital beam former 22.
Each of the ADCs 21 converts an analog signal output from a corresponding analog beam former 13 and transmitted through the cable 30 into a digital signal and outputs the digital signal.
The digital beam former (DBF) 22 performs a beam forming operation on the digital signals output from the eight ADCs 21.
The controller 23 may generate an ultrasound diagnostic image according to a signal output from the digital beam former 22.
In this conventional ultrasonic diagnostic system, when a number of transducers 11 increases, a number of analog beam formers 13 and ADCs 21 increases correspondingly and a number signals transmitted through the cable 30 also increases.
A recent ultrasonic diagnostic system includes a total of 9216 transducers arranged in a matrix form having 72 rows and 128 columns.
Therefore, when one sub-array includes eight transducers 11, a total of 1152 ADCs 21 are required. As fewer transducers 11 are included in one sub-array, more ADCs 21 are required.
In addition, the conventional analog beam former 13 must include a buffer at the output stage for stably providing an analog beam signal to an ADC 21. Generally, the buffer can be implemented using an operational amplifier.
In this way, in the conventional ultrasonic diagnostic system, there is a problem that the cost increases as the number of the transducers 11 increases.
Moreover, there is a problem that quality of a signal is degraded in a process of transmitting a large number of analog beam signals to the main body 20 through the cable 30.